title: ECG Changes in Smokers and Non Smokers-A Comparative Study.
abstract: BACKGROUND
  Tobacco consumption is the single most cause of the preventable deaths globally. Tobacco is consumed in the form of cigarettes. It contains nicotine which causes physical and psychological dependencies. Cigarette smoking increases the blood coagulability. Nicotine facilitates conduction block, re-entry and it increases the vulnerability to ventricular fibrillation. Hence, Nicotine and other components of cigarette can produce profound changes in the heart, which can be assessed by doing an ECG, which is the, cheapest and the most reliable method for assessing cardiovascular abnormalities.
  
  
  OBJECTIVE
  To compare the ECG changes between smokers and non- smokers.
  
  
  METHODS
  Eighty eight healthy male volunteers who were in the age group of 18-30 years, who attended the outpatients department of SBMCH were recruited for the study. Among the volunteers, 44 were smokers as per the ICD-10 criteria for substance abuse and the rest of the 44 were non-smoker subjects without any systemic illnesses and a drug and alcohol intake.
  
  
  METHODS
  After a thorough examination, all the subjects were asked to abstain from smoking and caffeine beverages, 2 hours prior to the taking of the ECG recording. The ECG was recorded in the lab of the Department of Physiology of SBMCH. The following parameters were assessed, namely, the heart rate, the p- wave, the PR interval and the QRS complex. The QTc (corrected QT interval) was calculated by using Bazet's formula. The QT interval, the ST segment and the T wave duration were evaluated in seconds. The results which were obtained were statistically analyzed by using the Students 't' test.
  
  
  RESULTS
  The analysis showed that QTc interval was shortened and that the QRS complex duration was widened in the smokers, although the values did not show any statistical significance. The heart rate was increased in the smokers, which was statistically significant. The RR interval, the QT interval and the ST segment were shortened in the smokers as compared to those in the non smokers, which was highly significant statistically.
  
  
  CONCLUSIONS
  All the above changes in our study were either a result of the acute effects or the chronic effects of smoking, which led to cardiovascular disorders which could be easily identified by the wave duration in electrocardiography. This may be used by physicians as a tool for counselling the smokers to stop smoking as early as possible. Smoking even a sin.
authors.affiliation: Associate Professor, Department of Physiology, Sree Balaji Medical College and Hospital , Chromepet, Chennai, India .
authors.forename: M R Renuka
authors.initials: MR
authors.lastname: Devi
authors.forename: T
authors.initials: T
authors.lastname: Arvind
authors.forename: P Sai
authors.initials: PS
authors.lastname: Kumar
keywords: Electrocardiography; Nicotine; Smoking